The present invention relates to torque transmitting apparatus in general, and more particularly to improvements in assemblies which are used to transmit torque between a prime mover and a hydrodynamic torque converter. Still more particularly, the invention relates to improvements in assemblies wherein a so-called lock-up clutch is installed in the usually bell-shaped housing of a hydrodynamic torque converter and the housing is connected or connectable to a prime mover, particularly to the internal combustion engine of a motor vehicle.
It is known to assemble the lock-up clutch of a combined hydrodynamic torque converter and lock-up clutch assembly from two disc-shaped walls which flank the clutch apply member of the assembly and wherein a damper with resilient energy storing elements is installed between such walls and the clutch apply member. The walls are further rigidly connected with a piston-like input element. Reference may be had to German Offenlegungsschrift No. 33 45 980 of Heinrich wherein an axially extending wall of the housing of the torque converter is provided with radially outwardly extending projections in mesh with the projections of a pressure applying disc. The latter is connected with a piston by a plug-in type coupling so that the pressure applying disc and the piston cannot rotate relative to each other. A friction generating lamination is riveted to a pair of disc-shaped walls which confine the energy storing elements, and such lamination extends between the piston and the pressure applying disc.
U.S. Pat. No. 4,177,885 to Ross discloses a modified assembly wherein an axially movable friction generating lamination (clutch disc) is non-rotatably secured to clutch apply piston. The latter is actuatable hydraulically and includes two parts with the energy storing springs of a damper between them. The two parts of the piston are rotatable relative to each other. This creates problems regarding the stability of the assembly, especially the stability of the two-part hydraulically operable piston, because the magnitude of axial forces acting upon the two parts of the piston is not the same. In addition, adequate sealing of the region where the two relatively rotatable parts of the piston are nearest to each other also presents many problems.